What is a Greenfield inferior vena cava (IVC) filter?

Updated: Oct 31, 2020
  • Author: Gary P Siskin, MD; Chief Editor: Kyung J Cho, MD, FACR, FSIR  more...
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Answer

Greenfield filter

In 1973, Greenfield et al introduced a new stainless steel filter. [2] The Greenfield filter has been on the market the longest, it is the most extensively evaluated filter, and it has become the criterion standard with which other IVC filters are compared. (See the image below.)

Greenfield filter. Greenfield filter.

The original Greenfield filter is conical, and it consists of 6 strands of 0.015-in, zigzag-shaped, 316L-grade stainless steel legs in a radial array, each with a hook at the end that anchors the filter to the IVC. The steel struts are 4.6 cm in length and are fitted to an apical hub, which is directed cephalad in the patient. The base is 3.0 cm in diameter with the legs separated by 11 mm in the deployed position. The filter is loaded into a 24F carrier with a 29.5F external diameter. Initially, the filter was placed via a surgical cutdown of either the right internal jugular vein or the right common femoral vein. Tadavarthy et al were the first to describe percutaneous placement of the Greenfield filter in 1984. [3]

The design of the Greenfield filter made it possible for thrombi to fill and occlude 70% of the filter cone, representing a volume of thrombus of approximately 4 cm3 (34.3% of total volume) without reducing the cross-sectional area by 50%. If the cone is filled to 80% of total volume, the reduction of cross-sectional area is 64%. The ability of this filter to trap clinically significant emboli has been demonstrated in several in vitro and in vivo studies.

In 1995, Greenfield et al reported on their 20-year experience with the Greenfield filter. [4] Recurrent PE was seen in 4% of 642 filter placements. The rate was comparable to that reported by other authors. Athanasoulis et al reported an overall recurrent PE rate of 4.9% in their experience with 7 different designs. [5] In the group of patients receiving the standard 24F Greenfield filter, 38 (8.4%) of 455 patients had recurrent PE. [5] Kantor et al reported access site thrombosis in 7 (41%) of 17 patients; this rate of thrombosis was associated with the large size of the delivery system. [6]

In 101 patients evaluated, Greenfield et al reported patency of the insertion site in 94 patients (93%). [4] In the same series, the authors reported an IVC patency rate of 96%. Migration of the filter was reported in 30-49% of patients. Allowing for respiratory variation, Greenfield et al readjusted the rate of migration of more than 3 mm to 8%. [4] Filter tilt, crossing of limbs, and limb fracture occur in a low percentage of patients, and most of these events are not associated with clinical sequelae.

Extension of the filter struts beyond the IVC, which is suggestive of perforation, has been noted in high incidence on computed tomography (CT) scanning. Proctor et al performed animal studies to evaluate the apparent vena caval penetration by the Greenfield filter. [7] All filters appeared to penetrate the IVC on cavography and CT scanning. Laparoscopy failed to demonstrate penetration, and histology revealed remodeling of the intimal surface of the IVC and thinning of the adventitia. [7] The authors further hypothesized that the presence of the filter caused adaptation and remodeling of the IVC to occur.


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